The present invention relates to disk drive data storage devices. More particularly, the present invention is directed to a disk drive with reduced latency to optimize performance and data throughput.
As the speed and performance of data processing systems is increased it is necessary to enhance the performance of disk data storage devices that include mechanical as well as electronic functions. Critical aspects are the access time as the transducer moves from track to track and the latency as the rotating media revolves to the position of the data addressed on the track. The latency problem can be resolved by higher rotational velocities of the media, but this is limited by constraints such as recording channel bandwidth, power consumption and spindle bearing life. These factors are particularly critical in smaller form factor devices wherein smaller media must rotate at a higher velocity to obtain the same linear velocities obtained using a larger diameter media and in portable devices where the size of the portable power supply is a criteria.
In various prior art devices the latency problem is addressed by redundant recording on the same or different tracks, the use of multiple transducer heads or most usually, a combination of multiple heads and redundant recording. U.S. Pat. No. 2,680,239 teaches the use of multiple transducer heads which address the same track. A switching device activates the head nearest the data of interest. In U.S. Pat. No. 3,103,650 multiple heads are used and in one embodiment four heads are used in conjunction with triplicate recording to read data stored on a track in one-twelfth of a revolution. U.S. Pat. No. 3,729,725 includes two transducer heads that write in separate regions (different tracks) with the data written by the second transducer head delayed by 180 degrees of rotation to assure that the beginning of the redundant data is displaced 180 degrees. A dual actuator system is used in U.S. Pat. No. 4,270,154 wherein the actuators are positioned 180 degrees apart around the disk periphery so that any read or write operation is done by the actuator that can first commence the operation.